attic venting

[mr.jake]

Ontario Canada

I recently purchased a home with a 32x48' pole shed that was used as a hobby barn. It was somewhat insulated, walls are spray foamed, attic is blown in. I strapped the walls and installed r12 batts and lined with steel. I am in the process of installing steel on the ceiling. I cut an access for the attic and went up to inspect, I found the blown in insulation was low in spots, 6" max, 2" min. I plan on blowing in another 6", but upon inspection I only see ridge vents for exhaust, the soffits are not perforated for intake, and there are no gable vents. What is the best way to go about adding an intake source for the attic? I Was thinking soffit vents, but would require digging out the insulation that has likely been blown into the soffits, making some sort of panel to prevent insulation from filling it when I blow more in. A gable vent seems easier but will it be sufficient intake for the ridge vents?

 

[Spudland_Dave]

AFAIK...You cant mix & match Ridge & Gable venting solutions... pick one or the other, when you mix n match you end up with all sorts of venting issues.

Since you already have a vented ridge...the easiest solution would be to remove the solid soffit and install perforated soffit, and as you mention install the soffit vent panels...no need to make em, they sell foam ones for less then $1.50 each, just staple in and blow your insulation...

**EDIT**here is a link to the Owens Corning Raft-R-Mates which I used...
http://www.owenscorning.com/roofing/accessories/ventilation/raft-r-mate/

There's a handful of brands & styles available...I used those cause that's what my building supplier carried..

 

[mr.jake]

The soffit seems appears to be installed behind the exterior steel, is it ok to buy panels and cut the holes in the soffit to fit? Say 2 8' panels per side?

 

[RM209]

Another alternative is to cut 3" or 4" holes and install round soffit vents. Although not as effective as ventilated soffit panels, they're easier and faster. However, regardless of the soffit ventilation system you choose, you'll still need to move the insulation in the attic so the vents aren't blocked.

RM209

 

[Spudland_Dave]

The soffit seems appears to be installed behind the exterior steel, is it ok to buy panels and cut the holes in the soffit to fit? Say 2 8' panels per side?

Might be...really depends on the roof in question. If you do a little googling, you'll find calculations & calculators for how much flow you need...and if you look at the specs when shopping you'll find perforated soffit panels are sold in various % openings... Same would hold true for what RM209 mention...a very good & easy idea...as long as you install enough of them to provide adequate ventilation, should be no issue.

 

[DC73]

Gable type vents might work if they were down low but would not be a good choice if they were up higher near the peak.

Given your ridge vents, the best choice is soffit vents. These are cheap (<$2 each) at Home Depot, etc:

http://www.homedepot.com/p/Master-F...-Eave-Soffit-Vent-in-White-EAC16X4W/100078188

They have other sizes as well.

Easiest way to install them is to get a hole saw for your drill and drill one hole for each of the 3 sections of vents. You could also pop two holes and jig saw out between them. If you put enough of them in, it doesn't matter if the total area is free or not. There are websites that will calculate the minimum total area required for soffit vents if you know the area of the ridge vents. You can always exceed the minimum.

DC

 

[mr.jake]

Thanks guys, I picked up some rafter mates and 8- 16x8 under eave vents. The trusses are 4ft center so 2 rafter mates fit between them spaces every 3rd. 4 vents per side under the eaves.